Abstract
This study examines the lanthanide calcium oxyborates Ca(4)LnO(BO(3))(3) (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb). The reported monoclinic structure (space group Cm) was confirmed using powder X-ray diffraction. The magnetic Ln(3+) ions are situated in well-separated chains parallel to the c axis in a quasi-one-dimensional array. Here we report the first bulk magnetic characterization of Ca(4)LnO(BO(3))(3) using magnetic susceptibility χ(T) and isothermal magnetization M(H) measurements at T ≥ 2 K. With the sole exception of Ca(4)TbO(BO(3))(3), which displays a transition at T = 3.6 K, no magnetic transitions occur above 2 K, and Curie-Weiss analysis indicates antiferromagnetic nearest-neighbor interactions for all samples. Calculation of the magnetic entropy change ΔS(m) indicates that Ca(4)GdO(BO(3))(3) and Ca(4)HoO(BO(3))(3) are viable magnetocaloric materials at liquid helium temperatures in the high-field and low-field regimes, respectively.